1. Field of the Invention
The invention is generally directed to the field of ophthalmic vision correction, and more specifically to wavefront-generated custom ophthalmic surfaces.
2. Description of Related Art
An ocular aberrometer, like the Zywave(copyright) wavefront analyzer (Bausch and Lomb Incorporated, Rochester, N.Y.) measures the wavefront aberration exiting a patient""s eye at the eye""s entrance pupil plane. This is accomplished by injecting a narrow beam of infra-red laser energy into the patient""s eye along the patient""s visual axis. The wavelength of the Zywave measurement beam is 780 nm. The laser energy diffusely reflects off the patient""s fovea and passes back through the eye completely filling the patient""s physical pupil. The optical components of the aberrometer relay the image of the physical pupil, which is by definition the entrance pupil, onto a Hartmann-Shack wavefront sensor (HSWFS). The HSWFS samples the wavefront at known intervals and a computer calculates a complete mathematical description of the patient""s exiting wavefront aberration. In the case of the Zywave, the mathematical description of the wavefront aberration is in the form of Zernike polynomials per Born and Wolf""s notation (Born and Wolf, Principles of Optics, 6th Edition, Cambridge University Press (1980 )). This wavefront aberration may be used to design a custom-correction solution for the patient, which may be accomplished through a contact lens, a spectacle, an IOL, an inlay, or laser refractive surgery.
An embodiment of the invention is directed to a method for determining an anterior or posterior surface parameter of an ophthalmic correcting surface (e.g., custom contact lens xe2x80x9cCCLxe2x80x9d; customized IOL) from a wavefront aberration measurement of an eye. A preferred aspect of this embodiment relates to determining an anterior surface parameter of a dry, CCL designed to operate at 555 nm. An algorithm sets forth the method comprising misalignment correction, chromatic aberration correction, and power shift correction due to differences between aberration measurement wavelength and peak vision wavelength, and differences between aberration measurement location and aberration correction location. In a preferred aspect directed to determining an anterior surface parameter of a dry, custom-correction contact lens, additional process steps include conversion of aberration polynomial coefficients to wet lens surface deformations, and compensation for dehydration-induced shrinkage.